diff mbox series

[v12,2/3] PCI: dwc: Implement general suspend/resume functionality for L2/L3 transitions

Message ID 20230821184815.2167131-3-Frank.Li@nxp.com
State New
Headers show
Series dwc general suspend/resume functionality | expand

Commit Message

Frank Li Aug. 21, 2023, 6:48 p.m. UTC 
Introduce helper function dw_pcie_get_ltssm() to retrieve SMLH_LTSS_STATE.

Add callback .pme_turn_off for platform specific PME handling.

Add common dw_pcie_suspend(resume)_noirq() API to avoid duplicated code
in dwc pci host controller platform driver.

Typical L2 entry workflow/dw_pcie_suspend_noirq()

1. Transmit PME turn off signal to PCI devices and wait for PME_To_Ack.
2. Await link entering L2_IDLE state.

Typical L2 exit workflow/dw_pcie_resume_noirq()

1. Reinitialize PCI host.
2. Wait for link to become active.

Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 .../pci/controller/dwc/pcie-designware-host.c | 71 +++++++++++++++++++
 drivers/pci/controller/dwc/pcie-designware.h  | 28 ++++++++
 2 files changed, 99 insertions(+)

Comments

Bjorn Helgaas Feb. 1, 2024, 4:50 p.m. UTC | #1 
On Mon, Aug 21, 2023 at 02:48:14PM -0400, Frank Li wrote:
> Introduce helper function dw_pcie_get_ltssm() to retrieve SMLH_LTSS_STATE.
> ...

> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 615660640801..91d13f9b21b1 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h

> @@ -364,6 +375,7 @@ struct dw_pcie_ops {
>  	void    (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
>  			      size_t size, u32 val);
>  	int	(*link_up)(struct dw_pcie *pcie);
> +	enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);

This has already been applied as
https://git.kernel.org/linus/4774faf854f5 ("PCI: dwc: Implement
generic suspend/resume functionality"), but this .get_ltssm() pointer
doesn't seem to be used anywhere.  Should we remove it until we need
it?

> +static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
> +{
> +	u32 val;
> +
> +	if (pci->ops && pci->ops->get_ltssm)
> +		return pci->ops->get_ltssm(pci);
> +
> +	val = dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0);
> +
> +	return (enum dw_pcie_ltssm)FIELD_GET(PORT_LOGIC_LTSSM_STATE_MASK, val);
> +}
Frank Li Feb. 1, 2024, 5:08 p.m. UTC | #2 
On Thu, Feb 01, 2024 at 10:50:25AM -0600, Bjorn Helgaas wrote:
> On Mon, Aug 21, 2023 at 02:48:14PM -0400, Frank Li wrote:
> > Introduce helper function dw_pcie_get_ltssm() to retrieve SMLH_LTSS_STATE.
> > ...
> 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index 615660640801..91d13f9b21b1 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> 
> > @@ -364,6 +375,7 @@ struct dw_pcie_ops {
> >  	void    (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
> >  			      size_t size, u32 val);
> >  	int	(*link_up)(struct dw_pcie *pcie);
> > +	enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);
> 
> This has already been applied as
> https://git.kernel.org/linus/4774faf854f5 ("PCI: dwc: Implement
> generic suspend/resume functionality"), but this .get_ltssm() pointer
> doesn't seem to be used anywhere.  Should we remove it until we need
> it?

Could you place hold on for a while? I am working on imx PCIe. One old
imx6 may need it!

If not, I will submit patch to clean it. My new patches depend on

https://lore.kernel.org/imx/ZbJ+tFPn3aOYHCwf@lizhi-Precision-Tower-5810/T/#t

All already reviewed, could you please pick up these, so I can continue
my futher work.

Another
https://lore.kernel.org/imx/20240201-pme_msg-v2-0-6767052fe6a4@nxp.com/T/#t
was under review.

After these, suspend/resume will become simple and common for all dwc
platform.

Frank.

> 
> > +static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
> > +{
> > +	u32 val;
> > +
> > +	if (pci->ops && pci->ops->get_ltssm)
> > +		return pci->ops->get_ltssm(pci);
> > +
> > +	val = dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0);
> > +
> > +	return (enum dw_pcie_ltssm)FIELD_GET(PORT_LOGIC_LTSSM_STATE_MASK, val);
> > +}
Bjorn Helgaas Feb. 1, 2024, 5:53 p.m. UTC | #3 
On Thu, Feb 01, 2024 at 12:08:23PM -0500, Frank Li wrote:
> On Thu, Feb 01, 2024 at 10:50:25AM -0600, Bjorn Helgaas wrote:
> > On Mon, Aug 21, 2023 at 02:48:14PM -0400, Frank Li wrote:
> > > Introduce helper function dw_pcie_get_ltssm() to retrieve SMLH_LTSS_STATE.
> > > ...
> > 
> > > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > > index 615660640801..91d13f9b21b1 100644
> > > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > 
> > > @@ -364,6 +375,7 @@ struct dw_pcie_ops {
> > >  	void    (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
> > >  			      size_t size, u32 val);
> > >  	int	(*link_up)(struct dw_pcie *pcie);
> > > +	enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);
> > 
> > This has already been applied as
> > https://git.kernel.org/linus/4774faf854f5 ("PCI: dwc: Implement
> > generic suspend/resume functionality"), but this .get_ltssm() pointer
> > doesn't seem to be used anywhere.  Should we remove it until we need
> > it?
> 
> Could you place hold on for a while? I am working on imx PCIe. One old
> imx6 may need it!
> 
> If not, I will submit patch to clean it. My new patches depend on
> 
> https://lore.kernel.org/imx/ZbJ+tFPn3aOYHCwf@lizhi-Precision-Tower-5810/T/#t
> 
> All already reviewed, could you please pick up these, so I can continue
> my futher work.
> 
> Another
> https://lore.kernel.org/imx/20240201-pme_msg-v2-0-6767052fe6a4@nxp.com/T/#t
> was under review.

OK.  I don't see .get_ltssm() used in that series either.  But if you
will need it soon, no point in removing it right now.

Bjorn
diff mbox series

Patch

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index cf61733bf78d..5c8cbc3afae4 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -8,6 +8,7 @@ 
  * Author: Jingoo Han <jg1.han@samsung.com>
  */
 
+#include <linux/iopoll.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
 #include <linux/msi.h>
@@ -16,6 +17,7 @@ 
 #include <linux/pci_regs.h>
 #include <linux/platform_device.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 static struct pci_ops dw_pcie_ops;
@@ -812,3 +814,72 @@  int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
+
+int dw_pcie_suspend_noirq(struct dw_pcie *pci)
+{
+	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	u32 val;
+	int ret;
+
+	/*
+	 * If L1SS is supported, then do not put the link into L2 as some
+	 * devices such as NVMe expect low resume latency.
+	 */
+	if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
+		return 0;
+
+	if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_ACT)
+		return 0;
+
+	if (!pci->pp.ops->pme_turn_off)
+		return 0;
+
+	pci->pp.ops->pme_turn_off(&pci->pp);
+
+	ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
+				PCIE_PME_TO_L2_TIMEOUT_US/10,
+				PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
+	if (ret) {
+		dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
+		return ret;
+	}
+
+	if (pci->pp.ops->host_deinit)
+		pci->pp.ops->host_deinit(&pci->pp);
+
+	pci->suspended = true;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);
+
+int dw_pcie_resume_noirq(struct dw_pcie *pci)
+{
+	int ret;
+
+	if (!pci->suspended)
+		return 0;
+
+	pci->suspended = false;
+
+	if (pci->pp.ops->host_init) {
+		ret = pci->pp.ops->host_init(&pci->pp);
+		if (ret) {
+			dev_err(pci->dev, "Host init failed: %d\n", ret);
+			return ret;
+		}
+	}
+
+	dw_pcie_setup_rc(&pci->pp);
+
+	ret = dw_pcie_start_link(pci);
+	if (ret)
+		return ret;
+
+	ret = dw_pcie_wait_for_link(pci);
+	if (ret)
+		return ret;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dw_pcie_resume_noirq);
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 615660640801..91d13f9b21b1 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -288,10 +288,21 @@  enum dw_pcie_core_rst {
 	DW_PCIE_NUM_CORE_RSTS
 };
 
+enum dw_pcie_ltssm {
+	/* Need to align with PCIE_PORT_DEBUG0 bits 0:5 */
+	DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
+	DW_PCIE_LTSSM_DETECT_ACT = 0x1,
+	DW_PCIE_LTSSM_L0 = 0x11,
+	DW_PCIE_LTSSM_L2_IDLE = 0x15,
+
+	DW_PCIE_LTSSM_UNKNOWN = 0xFFFFFFFF,
+};
+
 struct dw_pcie_host_ops {
 	int (*host_init)(struct dw_pcie_rp *pp);
 	void (*host_deinit)(struct dw_pcie_rp *pp);
 	int (*msi_host_init)(struct dw_pcie_rp *pp);
+	void (*pme_turn_off)(struct dw_pcie_rp *pp);
 };
 
 struct dw_pcie_rp {
@@ -364,6 +375,7 @@  struct dw_pcie_ops {
 	void    (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
 			      size_t size, u32 val);
 	int	(*link_up)(struct dw_pcie *pcie);
+	enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);
 	int	(*start_link)(struct dw_pcie *pcie);
 	void	(*stop_link)(struct dw_pcie *pcie);
 };
@@ -393,6 +405,7 @@  struct dw_pcie {
 	struct reset_control_bulk_data	app_rsts[DW_PCIE_NUM_APP_RSTS];
 	struct reset_control_bulk_data	core_rsts[DW_PCIE_NUM_CORE_RSTS];
 	struct gpio_desc		*pe_rst;
+	bool			suspended;
 };
 
 #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)
@@ -431,6 +444,9 @@  int dw_pcie_edma_detect(struct dw_pcie *pci);
 void dw_pcie_edma_remove(struct dw_pcie *pci);
 void dw_pcie_print_link_status(struct dw_pcie *pci);
 
+int dw_pcie_suspend_noirq(struct dw_pcie *pci);
+int dw_pcie_resume_noirq(struct dw_pcie *pci);
+
 static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, u32 val)
 {
 	dw_pcie_write_dbi(pci, reg, 0x4, val);
@@ -502,6 +518,18 @@  static inline void dw_pcie_stop_link(struct dw_pcie *pci)
 		pci->ops->stop_link(pci);
 }
 
+static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
+{
+	u32 val;
+
+	if (pci->ops && pci->ops->get_ltssm)
+		return pci->ops->get_ltssm(pci);
+
+	val = dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0);
+
+	return (enum dw_pcie_ltssm)FIELD_GET(PORT_LOGIC_LTSSM_STATE_MASK, val);
+}
+
 #ifdef CONFIG_PCIE_DW_HOST
 irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp);
 int dw_pcie_setup_rc(struct dw_pcie_rp *pp);